bashANYcurlhttpdebugginghealthcheck
bash
curl -s -o /dev/null -w '%{http_code}
' https://example.com/healthA compact pattern for extracting the final status code in shell scripts.
HTTP Common Errors and Debugging
Common HTTP status code comparisons, cURL debugging recipes, and troubleshooting patterns.
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cURL Debugging Patterns
Quick commands for checking status codes and redirects.
bashANYcurlredirectlocation
bash
curl -s -o /dev/null -D - https://example.com | grep -i '^location:'Useful for checking 301, 302, 307, and 308 behavior.
bashANYcurltiminghttp
bash
curl -s -o /dev/null -w 'code=%{http_code} time=%{time_total}
' https://example.comHelpful when distinguishing slow 200s from outright 5xx failures.
bashANYcurlapijson
bash
curl -i -X POST https://example.com/api/users -H 'Content-Type: application/json' -d '{"name":"Ada"}'A good baseline for reproducing 400, 401, 403, 415, 422, and 429 responses.
Common Web Error Scenarios
Frequent status-code situations in web apps and APIs.
textANYauth401403
text
401 = not authenticated / invalid credentials
403 = authenticated but forbiddenA very common distinction in API and admin-console debugging. `401` often includes `WWW-Authenticate`; `403` is about permission refusal.
textANY404410http
text
404 = not found
410 = gone permanentlyUse `410` when you want to communicate that the resource was intentionally removed and is not coming back.
textANYredirects301302307
text
301 = permanent
302 = temporary
307 = temporary, preserve method
308 = permanent, preserve method`307` and `308` are often better for APIs when method preservation matters.
textANY5xxproxygateway
text
502 = bad upstream response
503 = service unavailable / overloaded / maintenance
504 = upstream timeoutThese are some of the most common proxy and load-balancer errors.
textANYcacheetagconditional-request
text
304 Not Modified
412 Precondition FailedConditional requests with ETag or date validators often center around `304` and `412`.
More in HTTP Status Codes
HTTP 5xx Server Error Status Codes
Server error responses like 500, 502, 503, and 504.
HTTP 4xx Client Error Status Codes
Client error responses like 400, 401, 403, 404, 409, 422, and 429.
HTTP 3xx Redirect Status Codes
Redirection responses like 301, 302, 307, and 308.
HTTP 2xx Success Status Codes
Successful responses like 200 OK, 201 Created, and 204 No Content.
HTTP 1xx Informational Status Codes
Informational responses like 100 Continue and 103 Early Hints.
HTTP Status Codes Cheat Sheet
Comprehensive HTTP status code reference with meanings, examples, and debugging guidance.